Electric welding machine



July 3, 1928. 1,675,705

LE ROY H. HOFFER ELECTRI C WELDING MACHINE Original Filed April 10, 1924 2 Sheets-Sheet 1 1N VE N TOR LE/FOVfi/%FFER W TTORNEY July 3, 1928.

LE ROY H. HOFFER ELECTRIC WELDING MACHINE} ,MA TTORN y rangement of the electrodes and their cir-.

Patented July 3,d192 8;

L QSTTS NT OFFICE.

LE ROY H. Henna. on nnooxt'a'n, new loan, ASSIGNOR T0 moms a. MURRAY, or

- BROOKLYN, .NEW YORK.

' nnnc'rnrc WELDING MACHINE.

Original application filed April 10, 1924, Serial No. 705,419. Divided and this application filed August 18, Y i927. Serial No. 212,621.

ent application.- The object ofthe inven= tion is to provide a convenient and safe arcuit-connecting devices.

The accompanying. drawings illustrate embodiments of invention.

.Fig. 1 is a side elevation partly in section illustrating one end of the machine;

Fig. 2 is a plan of Fig. 1;

Fig. 3 is a vertical section on the line 33 of- Fig. 2;-

-Fig. 4 is a vertical section on the line 44 f so Figs. 5 and 6 are opposite side elevations of a clamping electrode;

Figs. 7 and 8 are respectively a plan and side elevation of an end electrode.

The machine is provided with two sets of welding mechanisms at opposite ends of the head. Only one of these is illustrated, the opposite one being substantially identicaL- The purpose of eachwelding mechanism is to weld an end plate or flange on a differential housing. The drawings show the positions of the parts at the completion of the weld. I

Upon the upright bed 1 isa casting 2 on which is an internal chuck 3 to hold the housing at the centre. The transformer 4 has its core 5 fastened to the bed of the machine as'shown' in Fig. 3.

Mounted on the transformer are two transverse guides 6 in which clamping electrodes 7 slide transversely so as to clamp between them an .end of the work 8. The electrodes are forced 'latcrally inward by hand operated cams 9 which carry pins engaging hooks '10 for withdrawing the electrodes. The electrodes at their outer ends have forwardly projecting arms 11 which carry' inwardly projecting switch blades 12 which in the clamped welding posit-ion engage'switch blades 13 carried by a fixed bracket 14 which is mounted on the transformer and connected to a terminal thereof. On its face each of these electrodes has a block 15 recessed for direct engagement and clamping of the work. Its body portion may be water cooled as by means .ofa U- extraordinarily high amperage or density" for a very brief pcriodmf ,time(Reissue No. 15,456, dated, October 10, 1922). Such an end plate is shown at 18 (Fig. 8) held in place in a recessed block 19 on therend of an electrode 20 which is Water cooled by means of a central recess 21 and pipes 22 for circulating water therethrough.

The machine is designed Each of these endelectrodes is mounted to slide longitudinally on a plate 23 (Fig.

'1) which is supported on a bracket 24 and insulated from the transformer. The electrode has lateral arms 25 at both sides carrying forwardly extending switch blades 26 which in the advanced position engage blades 27 carried in pairs on brackets 28 mounted on the top of the transformer and connected with one of its terminals (the terminal oppositeto that which leads to the clamping electrodes) so that when the -end plate and the housing are brought to gcther and the circuit is closed the welding current is passed across the Joint. 1

The provision of a number of switch blades along the sides of the moving electrode serves to equalize the distribution of the current to difi'erent parts of the electrode'and around the end plate. Similarly theprovision of a number of switch blades trode forward or retracting it. This mecha nism is described in full in the parent application; p

In 0 crating the machine, the housing and the end plates are put in position,.the clamping electrodes 7- arepressed inward about the ends of the housing. The'solenoidsare then energized to put a continuing pressure on the end electrodes and finally the pri:

mary circuit of the transformers is closed so as to.cause a Weldin current to flow through the electrodes; '1 he pressure on the end electrodes continues and these are advanced until at a certain point the primary circuit ofthe transformers is broken.

The pressure on the work-may be continued while, it is'cooling after'the' welding current is ofl'. Finally-the controls'areoperated to relieve the pressure and-t0 retract the end electrodes and the clamping electrodes. The completedhousing is then taken out and a new one'introduced for the next.

cycle of operations.

The supports for the movable electrodes, the clamping electrodes 7 and. the end elec-v trodes 20 are insulated from the secondary transformer. This permits the making of the supporting plates and the sliding bearings of steel or brass which have a better wearing quality than copper. The electrodes themselves will generally'be of coper. 7 p Various modifications ma be made by those skilled in the ,art wit out departing vfrom the invention as defined in the following claims. A

What I claim s: v

' 1. In a welding machine'for tubularwork the combination of electrodes at op osite sides of the workand movable towar each.

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other to engage and clamp the work between I them, switch blades carried by said electrodes at different points in their cross seccurrent, a transformer and tw'o sets of stationary switch blades connected to one terminal of the transformer and located in positions to be engaged by the switch blades i carried-by the respective electrodes as the latter are moved toward each other so as to distribute the'current'equally t0 the .two electrodes and the opposite sides. of the work.

2. In a weldin machine for tubular work the combination of electrodes at op osite sides oft-he workland movable towa r each other to engage and clamp the work between;

them,- switch blades carried by said electrodes at different points in "their cross section so as to equalize the distribution of of-t e tubular'part of'the work, said endwise movable electrode having similar switch blades and correspondingly locaft'd'fstationar. switch blades connected to the hthcr terminal of the transformer and co-operating with the switch blades of said endwisc movable electrode,

tion so as to equalize the distribution of In witness whereof I have hereunto signed my name. L

LE ROY H. HOFFER. 

